The National Surgical Adjuvant Breast Project (NSABP) was established in 1958. The objectives of the cooperative group remain as originally defined and are being expanded. They have been (a) to evaluate the efficacy of various modalities employed in the treatment of primary breast cancer, (b) to estimate the worth of new and promising surgical adjuvant therapies, and (c) to gather biologic and other pertinent data from patients with such tumors. The present application is submitted so that we may continue our efforts directed toward these objectives. In addition, this grant will have as its prime objective the enhancement of the multidisciplinary aspects of the NSABP so that it may more effectively implement protocols utilizing multidisciplinary therapy for the treatment of primary breast cancer. Funding for this grant will also permit the continued follow-up of about 3,000 patients on existing primary breast cancer protocols and continuing active accrual to 3 new protocols directed towards Stages I and II breast cancer. The breast cancer protocols currently active are: (a) Protocol B-06; a trial to compare the worth of segmental mastectomy with and without breast radiation with total mastectomy plus axillary dissection. All patients with positive axillary nodes will receive adjuvant chemotherapy; (b) Protocol B-09: a trial to determine whether the anti-estrogen Tamoxifen when combined with chemotherapy improves the result of chemotherapy alone; and (c) Protocol B-10: a trial to compare the value of the immunopotentiator C. parvum combined with chemotherapy vs. chemotherapy alone. Protocol studies that are in the follow-up stage number 4. They are Protocols B-04 (surgical trials), B-05, B-07, and B-08 (all chemotherapy trials).